Server Based Computing (SBC) and hosted Virtual Desktop Infrastructure (VDI) solutions are used in enterprises today to provide a virtualized Windows desktop hosted in a datacenter to (remote) end users. These virtual desktops are hosted in the central datacenter and accessed by users remotely through a remote display protocol over a network such as a LAN, WAN, mobile broadband and the Internet. Both the VDI and SBC desktops run on shared server hardware in the datacenter. A virtual machine monitor, or hypervisor, creates and runs virtual machines in the datacenter, and makes it possible to run multiple virtual instances of a Windows desktop.
Currently, the VDI concept is often preferred over SBC, as this gives the most flexibility since each user works on their own personal Windows desktop instead of a shared and standardized Windows Server desktop. In SBC, multiple desktop sessions are provided from one Windows server instance. Consequently, the operating system is shared by the users. It is possible to provide a SBC environment while Windows Server is directly installed on the server hardware without a hypervisor. This is commonly called a bare-metal installation of Windows Server. However, it is common to virtualize Windows servers and run a SBC environment virtualized on the server hardware.
As a result, with both SBC and VDI, each desktop session is sharing all server hardware located in the datacenter, including the hypervisor, CPU, memory, network and storage. These server resources are limited per definition, and as a result each solution has a specific capacity. It is difficult if not impossible to predict what the capacity will be of SBC and VDI solutions, when the combination and specific configuration of hardware and software is not fully tested. This is an important topic to IT organizations, because ultimately it is necessary to understand how much hardware (server, network and storage) is required to be able to provide desktops to a given number of users.
One difficulty in making this determination is that there is very large number of different combinations possible to build a VDI or SBC environment. Both on a hardware and software level, technology is continuously innovated to improve the user experience and reduce hardware and software costs. Although functionally the same for the end-user, the underlying technologies differ wildly for each solution, and there are many vendors actively releasing new products in the VDI and SBC market.
Much of the innovation has either a positive effect on the capacity of the system (example: Storage IO accelerators) or negative effect on the capacity of the system (example: multimedia support for greater end-user experience). In addition, specific settings in the software and hardware can have a significant impact. It may be that the stack of hardware and software for the VDI and SBC solutions is identical in two different organizations. Still, the manner in which Windows and applications are configured and used can be fundamentally different in each organization. As a result, the capacity of two superficially identical VDI environments in two organizations can have a different capacity in practice.
Also, a VDI or SBC solution is comprised of many different software and hardware elements from different vendors that affect performance and capacity. Examples of these are: the virtual desktop broker software, the hypervisor, security software, office and business applications, server hardware, (shared) storage and network (both LAN and WAN).
It would be advantageous to be able to predict, before actual users are working in a deployed virtual desktop environment, what the capacity is of an individual server and a complete environment in the datacenter.